The present invention relates to an eyeglass lens processing shape obtaining method of obtaining an eyeglass lens processing shape for attaching a prescription lens having refractive power to a rim of an eyeglass frame, in place of an original lens having been fitted to the rim.
Eyeglass frames for sunglasses, eyeglass frames of types in which a user is able to simply exchange lenses of different colors (a lens exchange type, and a lens attachment and detachment type) are appearing on the market (for example, see JP-T-2006-510065(WO2004/059367A2). A rim of the eyeglass frame for the sunglasses is formed with grooves for fitting a part of an edge of an original lens. Recently, in place of the original lens fitted to the rim of the frame, there is a higher demand for replacement with the prescription lens (lens with a refractive power). In the case of the original lens for the sunglasses, the thickness of the original lens is uniform, and the rim is formed with a groove which is larger than the thickness of the original lens. However, in a case of inserting the prescription lens (the refractive power lens) into the groove of the rim, since the width of the peripheral edge portion of the prescription lens is greater than the width (thickness) of the original lens, there is a need to perform the processing so as to insert the peripheral edge portion of the prescription lens into the groove of the rim. In other words, there is a need to process the peripheral edge portion of the prescription lens to form a portion to be inserted into the groove of the rim and a stepped portion which is cut off so as not come into contact with (interfere with) the rim. The processing of forming the step is called a step processing. As an eyeglass lens peripheral edge processing apparatus which promotes the automation of the step processing, a device disclosed in JP-A-2009-131939 (US2009-142993A1) is suggested. The device disclosed in JP-A-2009-131939 includes a peripheral edge processing tool capable of performing the step processing.